<?php
include("admin/cls/cls_user.php");
$user_id=$_POST['user_id'];
$comment=$_POST['comment'];

if( isset($user_id) && !empty($user_id)   && isset($comment) && !empty($comment) ) {

$user = new cls_user ();
$var=$user->uploadComment($user_id,$comment);
echo"
<script>
document.write(window.location='comments.php');
</script>";
} 

else {

echo "Error, no ha introducido todos los datos";

}
?>